Solar activity has important effect on terrestrial environment in which human population lives. Long-term and short-term periodicities in solar activity had influence on secular climate changes, little ice ages and climatic optima. The article summarizes briefly the results and methods of historical climatology. The text resumes the methods of research of the solar activity variation over the last 1500 years, through physical methods as well as through preserved written sources. The basic mechanisms of the effects of solar activity on terrestrial environment and human population are explained as well as the predictions of the upcoming solar activity. This may indicate that we are currently at the beginning of another long-term solar minimum., Kateřina Podolská., and Obsahuje bibliografii
The bicentennial varia tions of the Earth rotation consist of several oscill ations with most known periods 178.7a (Jose cycle), 210a and 230a (de Vries cycle); they are driven by the solar cycles which affect climatic variations, followed by global environmental changes. These periods are close to the higher harmonics of millennial Hallstatt cycle (2300a), so the proper separation between the indi vidual bicentennial cycles needs time series longer than 2300a. The bicentennial variations of the Universal Time (UT1) in relation to the Terrestrial Time (TT) are investigated using reconstructed time series of the Total Solar Irradiance (TSI) for the last 9300a. A linear regression model of TSI influe nce on the UT1 and the Mean Sea Level (MSL) bicentennial variations are created. The parameters and time series of the bicentennial UT1-TT oscillations for the last 9300a are determined., Cyril Ron, Yavor Chapanov and Jan Vondrák., and Obsahuje bibliografické odkazy